Chem Film／Alodine Finish： All You Need To Know About Chromate Conversion Coatings

June 24, 2023

Surface finishing in the manufacturing industry improves a product’s functionality and aesthetics and enhances other attributes. For example, it is suitable for protecting products from corrosion, abrasion, etc. Among the several processes used by different manufacturers, alodine finish has unique properties as the surface finishing option boasts incredible productivity, ease of operation, longevity, etc.

Here, we will introduce you to everything you need about Alodine finishing. This will include the principle,?applications, design considerations, and other things that make it one of the best surface finishing options you can think of for your product.

Contents hide I What is Alodine? II How Does Alodine Finish Work? III Types of Alodine Chromate Conversion Coating IV Alodine vs. Anodizing: What's the Difference V What are the Characteristics of Alodine Finish VI Applications of Alodine Finish VII Design Considerations: How to Make Alodine Finish Looks Good VIII Conclusion IX FAQs

Alodine is a chemical substance dissolved in aqueous solutions to produce a gel applied to metals such as aluminum alloys. It forms a coating that protects the metals and enhances their aesthetic appeal. Other functions of alodine finish include:
-Act as a base for painting and priming
-Helps in preserving electrical conductivity.

However, the name “Alodine” has been trademarked by Henkel Surface Technology. The generic name for this type of chem film is “chromate conversion coating”.

Alodine or chromate conversion coating is a simple process that leads to passivation. The process is straightforward. However, it depends on the alodine you are working with.

If you are using the Type 1 MIL-DTL-5541 standard, follow the steps below to apply alodine chemical conversion coatings on your metal parts.

Step #1: Clean the Metal Product

Degrease the first part to eliminate small impurities such as oxides, greases, oil, and heavy metal contaminant. After degreasing, rinse the part and dry it. Degreasing the product ensures that the chemical conversion coating sticks well and is even.

Step #2: Etch the Product

Etch the part of the metal product where you don’t want the chemical conversion coatings to be. Etching will cover these areas so that you can correctly and accurately coat the metal product. Rinse and dry the product again.

Step #3: Deoxidize

Oxygen is another contaminant you should avoid in alodine coating or other chemical conversion coatings. Remove oxygen by putting the part through a deoxidization process. This will remove oxygen, oxides, and other related chemicals. Rinse the part to remove the deoxidizing agent.

Step #4: Apply Chem Film Coat

Immerse the part in a chemical bath containing the alodine compound dissolved in an aqueous solution for a predetermined time. The time chosen depends on the part and the thickness desired. You can also use a brush or spray the part with the alodine.

Step #5: Final Wash

After applying the alodine chemical conversion coatings, rinse with water to remove the excessive coating. Then rinse with warm water to get a perfect surface finish. Allow the part to dry.

The Type 2 MIL-DTL-5541 standard is slightly different and has two variations: Acid clean and Alkaline clean process. Follow the steps below on applying the alodine finish on the part.

Acid Clean Process

Clean the product using acidRinse with waterApply the Type 2 alodine

Alkaline Clean Process

Clean the product using an alkaline solutionRinse with waterDeoxidize to remove oxygen contaminantRinse with waterApply the Type 2 alodine

There are several types of alodine, each with unique chemical composition. Common ones include Type 1 and Type 2 of the MIL-DTL-5541 standard, AMS-C-5541, MIL-C-81706, and AMS-2473 and 2474.

Of the five above, the two most typical ones in the manufacturing world are:

Type 1 MIL-DTL-5541 standard contains hexavalent chromium that produces a brown or gold film or sometimes a clear film. Also known as hex chrome due to the presence of hexavalent chromium, it was the conventional alodine for many years until the advent of Type 2 and other safer chemicals.

Hexavalent chromium is a hazardous chemical labeled by OSHA as carcinogenic. Therefore, some countries do not permit its use. Those that permit its use require processing permits, proper ventilation, and disposal method.

MIL-DTL-5541 Type 2 is the standard alodine in the world. Unlike Type 1, it contains trivalent chromium, titanium, or zirconium. Therefore, it is referred to as hex-free chrome. Also, Type 1 does not come in color as parts subjected to the coating are clear. Type 2 has the following advantages over type 1

It has a better safety profileIt occurs at a lower temperature than Type 1The application process is easier, faster, and a more straightforward

Both alodine and anodizing are conversion coating processes and are sometimes confused with each other due to their similar production process. They involve immersing the part in chemicals and allowing the coatings to form. Cemented Carbide Inserts However, both surface finishes are different. Below are a few differences between both processes.

The difference between alodine and anodizing becomes clearer by understanding the processes themselves. Anodizing is an electrolytic process that involves coating a metal with its oxide. For example, anodizing aluminum makes the part more corrosion and wear-resistant. This is different from chromate conversion coatings, a simple chemical process that doesn’t use electrical currents.

The effect of the alodine finish on the metal part dimension is very small, with thickness between 0.00001 to 0.00004 inches. This is unlike the anodizing that forms a thicker layer (ranging from 0.00001 in Type 1 anodizing to 0.001 in Type III anodizing.)

Purpose

Both conversion coating methods are suitable for achieving Carbide Aluminum Inserts corrosion resistance. However, anodizing has a better aesthetic appeal. Hence it is more suitable for decorative purposes.

Alodine finish is less costly than anodizing. However, you should factor in the different types of alodine, the size of the metals, and other implications as they can also impact the price.

Alodine finish is a common industrial surface finish process due to its simplicity without a loss of function. Below are a few characteristics that make it one of the best to consider.

One of the unique things about the alodine finish is the formed coating film. This is beacuse the coating film is very thin, usually between 0.5 and 4 microns. It can act as a corrosion-resistant surface, primer, or base without altering the part dimension

Applying the chromate conversion coating, especially Type 2 standard, can occur at room temperature. Therefore, manufacturers and designers don’t need to stress over applying the coating. Also, it reduces the energy consumed, reducing the cost of acquiring such energy.

The type of alodine you are using will determine the toxicity. The hex chrome is very toxic and considered by OSHA a carcinogenic material. However, the hex-free chrome is not toxic. Nevertheless, handle both with care and dispose of them using the stipulated regulations according to government bodies.

Applying the chem film onto a metal part should only take a few minutes. However, this depends on the method you are using.

Aside from making the metal corrosion-resistant, an alodine finish also makes the metal conductive. Parts subjected to the process are also useful as a base for priming and paints.

Alodine finishing is widely applicable in several industries in the manufacturing world. Below are a few applications of the surface finishing option.

One of the most common alodine coatings applications is the surface treatment of CNC precision machining parts. CNC fabricated metal parts are preserved from corrosion and surface-acting contaminants with alodine coatings. What makes alodine ideal is that there is no significant alteration to the final dimension of the metal parts.

As a result, alodine coating is an important surface finishing as it protects aluminum alloys and other materials used in the aerospace industry. Parts used in making aerospace parts, such as aircraft hulls, landing gear, shock absorbers, etc., are exposed to atmospheric gases at high altitudes. This can lead to the corrosion of such parts.

Parts used in making products used in the military and defense industry must resist corrosion. For example, boat interiors and other mechanical parts in the navy are often invaded by salt water, thereby susceptible to corrosion. Therefore, alodine coatings protect aluminum and other important materials.

Chromate conversion coating is a very straightforward process. However, you need a few design considerations to make the alodine finish look good. Below are a few design considerations to consider:

-Plugging threaded/reamed holes

This might be needed if tolerance is very tight. However, most manufacturers shouldn’t consider it as chromate conversion coatings’ thickness change is minimal.

-Deburring

You can improve the consistency of the coating by deburring the surface. Deburring will remove or hide small machine marks on the parts, making the surface smoother and the finishing of better quality.

-PH and temperature

Ensure you are using the alodine finish at the right pH and Temperature specified in the specifications. Using them otherwise would lead to non-adhering coatings.

-Bad alodine material

Using the wrong alodine finish can also affect the quality of the product. Therefore, ensure you don’t have a bad can of material. You can ascertain this by asking the manufacturers for the QC sample and checking whether they meet your specifications. You can also ask for a test service.

In conclusion, among the different surface finishing procedures used by different manufacturers, alodine finishing boasts incredible productivity, ease of operation, and quality product.

Most importantly, the process involves coating the metal part to protect it from corrosion, act as a base or primer, and improve its electrical conductivity. Chromate conversion coating has many applications due to its thin coating, which is ideal for coating precision parts.

So, if you are looking for a chromate conversion coating for your machined parts, Estoolcarbide is the right company to meet your alodine finish needs with high standards. Meanwhile, we can make sure your all products are properly surface finished and look great.

What is an Alodine finish?

Alodine or chromate conversion coating is used for metal corrosion protection. It also acts as a base, primer, or for presenting the metal’s electrical conductivity.

How do you apply Alodine Chromate coating?

There are different styles of applying alodine. You can brush, dip/immerse, or spray the coating on the metal part. Of the different styles, immersion is the most common.

Is it Alodine finish important for CNC machined parts?

Yes, CNC machined parts must be precise even though subjected to any surface finishing option. Of the different surface finishing options available. Chromate conversion coating is a surface treatment that can help with corrosion protection without altering the metal part’s dimension. It also helps reduces poor electrical resistance.

How thick is chromate conversion coating?

The chromate coating thickness ranges from 0.25-1.0 μm or 0.00001-0.00004 inches.

The Tungsten Carbide Blog: http://loriharrie.jugem.jp/

Understanding and Working Around with CNC Machining Tolerances

April 14, 2023

If there is one thing that CNC machining is known for, its accuracy and precision. However, like any other process, there may also be variations in the dimensions of the parts being produced. Factors like material used, spindle alignment, tooling accuracy, work holding rigidity, coolant usage, and shape complexity significantly affect the dimensional accuracy when machining.

Accepting the variability of the dimensions produced, engineers and designers set specific CNC machining tolerances for the parts during the design process to avoid impairing the final product’s functionality and quality. Read on to learn more about machining tolerances, why we need them, and how to achieve a precise and accurate CNC part.

CNC machining tolerances are the limits set to identify if a part is acceptable or deemed as scrap. Basically, this is giving perspective on how much room for error you have when machining a part. Why is this so important?

Of course, the essence of doing business is minimizing costs as much as possible while still maintaining the needed quality for the parts. Generally, the tighter Cermet Inserts the tolerance you set, the more expensive it gets. Parts with a very tight machining tolerance call for added processes like grinding or superfinishing. For a less strict tolerance, a part can be finished just through the basic machining processes. What does tolerance have to do with cost?

Defining your tolerances helps avoid overshooting costs for machining a part. Only the critical areas of the part are labeled with tight tolerances. This reduces the cost of components produced by establishing what features matter and what do not.

Most parts being manufactured through machining, in some way, will be interfacing with other machined components for assembly or other purposes. Interchangeability is very critical for fabricating high-volume parts. It allows components to fit any assembly of the same type.
The Deep Hole Drilling Inserts simplest examples are the mating parts. A shaft is controlled, so it should still fit into the mating part, given any dimension variations. The same is through with the sleeve.

Most parts being manufactured through machining, in some way, will be interfacing with other machined components for assembly or other purposes. Interchangeability is very critical for fabricating high-volume parts. It allows components to fit any assembly of the same type.
The simplest examples are the mating parts. A shaft is controlled, so it should still fit into the mating part, given any dimension variations. The same is through with the sleeve.

Machined parts are controlled by tolerances because some features on a part are vital to its functionality. In many fixturing applications where location and sizes are critical, any variation that is not within tolerance will make a fixture defective and unusable.

Tolerances in manufacturing drawings are expressed differently, depending on what feature is being controlled and the engineer’s design intent. Below are the most common types of machining tolerances used in the industry:

This type of tolerance allows one directional variation only, hence unilateral. Let’s work on a simple example. Given a shaft that needs to fit into the internal diameter of a sleeve. The shaft diameter should not exceed the sleeve’s inner diameter, so when applying unilateral tolerance on the shaft, you control it by allowing only negative variation from the nominal size (e.g., given the shaft diameter is 1.000 in, applying unilateral tolerance will look like this: 1.000 +0/-.005 in). Unilateral tolerances are commonly used in components that have mating parts.

In contrast to unilateral tolerance, bilateral tolerances allow both plus and minus variations from the nominal size. Applying bilateral tolerance on a 1.000” dimension would look like this: 1.000 +/- .005. This type allows equal distribution of the variation permitted for the piece part. Bilateral tolerances are commonly used, but not limited to, to call out external dimensions.

Limit tolerance is expressed as a range of the minimum dimension and the maximum allowable dimension. The dimension for the manufactured part should lie in between these values. Limit tolerances in manufacturing drawings will look like these: .995-1.005 in.

These are the standards set for the most common components in the industry like thread sizes, pin sizes, pipes, steel bars, and many more. General tolerances are usually regulated by various standards governing associations like ASME, AISI, ISO, and many more. The control and specific dimensions for these tolerances are typically listed in table references.

Some example includes:
● Calling out threads as coarse, fine, extra-fine (UNC, UNF, UNEF)
● Calling out shaft and hole dimensions as to fit tolerances like H7/g6, G7/h6, H8/g6 (in simple terms: slide fit, interference fit, snug fit, force fit, free-running fit)

This type of tolerancing uses feature control frames in depicting specific dimensional and form tolerances. This paves the way for a clearer depiction of controlling the features of the CNC parts, including flatness, straightness, runout, perpendicularity, and position callouts. GD&T is very useful for designers in specifying their required CNC machining tolerances.

If you have a part you are looking to outsource, you should look for a trusted and established machining facility to be your partner. Not all CNC machining services providers have the capability to deliver extremely precise and accurate parts with tight tolerances. Facilities with the most experience and high-end equipment are at an advantage for this.

Work holders play a great part in ensuring that the CNC machining tolerances are achieved. These are responsible for holding the part in place while being machined and used as reference points regarding locations.

Cutting tools are one of the reasons behind the dimension variations in a work part. This may be caused by wrong cutting tool utilization, tool deflection, and dull cutting edge. Tool deflection usually occurs on long-ended features like deep holes and long shafts. Also, dull cutting tools put your parts in an undesirable position and threaten your spindles’ accuracy.

Dimension accuracy can be difficult to attain for some materials and might be easy for some. Take note that materials behave differently while being exposed in the machining environment.

CNC machining tolerances are an important aspect of ensuring the quality and functionality of the parts produced by setting limits on up to what extent the dimensional variations are allowed.The application of tolerances in fabricating piece parts is important to control the cost, ensure their interchangeability, and maintain functionality.The most common types of machining tolerances are unilateral tolerance, bilateral tolerance, limit tolerance, general tolerance, and GD&T.It is also essential to consider some factors when working with tolerances. These factors include work holders, material, tooling performance, and the selection of preferred machining facility.
The Tungsten Carbide Blog: http://elviscarte.jugem.jp/

BIG KAISER’s Speroni Presetters Meet Digitally Shifting Demands

BIG KAISER tool presetter partner, Speroni S.p.A., has announced a new partnership with a leader in the digital shift toward operational efficiency, MachiningCloud. Customers can Cast Iron Inserts now directly access complete cutting tool data from leading manufacturers through Speroni presetter controls.

“We are always looking for innovative solutions which will deliver significant improvements to the world of manufacturing,” says Speroni CEO Andrea Speroni. “This integration with the revolutionary MachiningCloud intelligent manufacturing application will deliver exceptional value to our end users.”

The partnership connects Speroni’s interface to MachiningCloud’s cloud-based digital product data hub that houses the most up-to-date equipment data. Automatically populating individual presetters saves time and decreases the risk of human error in tooling setup. MachiningCloud’s tool search feature allows end users to search the manufacturer’s catalog for new tools not presently in inventory.? Plus, customers can find Carbide Steel Inserts up-to-date recommendations on cutting speeds and assembly conditions for given materials directly from manufacturers.

“The mission of MachiningCloud is to make much needed tooling information more easily accessible to those who need it,” says MachiningCloud Cloud Evangelist, Christophe Rogazy. “A partner like Speroni, which operates with a very similar mission, will bring even greater benefits to manufacturers.”

MachiningCloud’s tablet and desktop applications give users a variety of convenient features, including selector, configurator, advisor, tool package/job management and reporting/commerce settings. The software interfaces with CAM, tool-crib management, purchasing, scheduling and ERP software, giving users access to a rich set of features that ensure a greater and more seamless flow of information throughout the shop.

For more information about Speroni, visit?www.speronispa.com. For more information about MachiningCloud Intelligent Manufacturing, visit?www.machiningcloud.com.

The Tungsten Carbide Blog: https://neilmeroy.exblog.jp/

CNC Turning and Milling： A Quick Guide to Understanding Their Differences

October 7, 2023

Most CNC machines use CAD and CAM software to fabricate precise and accurate components. However, the main challenge in modern manufacturing industries is understanding the operation of these machines. CNC turning and milling remain the commonest CNC machining Carbide Steel Inserts processes manufacturers apply to fabricate various components.

While the turn-mill operations overlap, they apply distinct machining methods. Continue reading as we examine the differences between CNC turning and CNC milling and their applications to help you make an informed choice.

Turning is a popular form of CNC machining process. CNC turning basics comprise affixing suitable materials in a rotating chuck. At the same time, the cutting tools fed to the workpiece remove the material until the needed shape is formed. Generally, CNC lathes or turning centers apply in turning operations.

Before the advent of computer programs, manufacturers operated lathes by hand, making them more labor-intensive. Thus, the innovative development of Computer Numerical Control (CNC) uses pre-programmed software to automate various processes on suitable workpieces. They include drilling, boring, grooving, parting, facing, knurling, etc.

A CNC lathe comprises a chuck and multi-sized cutting tools. Before using the machine, the machinist must set the cutter’s speed, feed rate, depth, and other important instructions to get the desired shape component automatically. During the turning operations, the chuck helps hold the workpiece in place, while the cutting tools attached to a turret move toward the rotating workpiece to remove excess material where required.

Most manufacturers use CNC lathes with only one turret and apply suitable cutting tools individually to complete many projects on one side. In other cases, some experts also use turning centers with a main spindle and sub-spindle for more rapid operations. In this configuration, the main spindle moderately machines the material. It then gets directed to the sub-spindle to perfect the work on the other side of the desired component.

CNC milling basics involve using computer software to automate and control milling tools. It combines various processes such as face, angular, or plain milling to fabricate exact components from suitable materials.

A CNC mill comprises a vertical spindle and revolving head that contains a rotary cutter fed to the workpiece. During CNC milling operations, the mill holds the workpiece stationary on the machine bed. Then, the spinning multi-point cutting tools get fed to the workpiece’s surface to progressively remove excess materials in a controlled setup until almost any desired shape gets formed.

Furthermore, CNC mills are available in different configurations. They include the 3, 4, or 5-axis mills. While the traditional 3-axis CNC mill directs the cutting tool in three angles – X, Y, and Z, the modern 5-axis CNC milling machine enables the cutting tool to move in up to five directions.

Note that the higher the number of cutting angles or axes, the more the dimension of flexibility, enabling CNC mills to fabricate custom components with complex geometry and intricate details. That way, you’ll find that using the 5-axis machine is more expensive due to its flexible features, impacting the final cost of intricate milled components.

The most significant difference between CNC milling and CNC turning lies in the movement of the cutting tool and workpiece. In CNC turning operations, the workpiece revolves or rotates at a set speed, whereas the cutting remains stationary. On the flip side, CNC milling involves holding the workpiece in a fixed position while the cutting tool spins around it to subtract excess materials.

Concisely, this variation in the cutting tool or workpiece movement reflects the differences in dimensions and shapes that each machining method can best produce. Below are some other notable differences between CNC turning and milling:

CNC turning uses a single-point cutting tool, while CNC milling processes use multi-point cutting tools.

CNC milling includes machining processes such as plain, angular, and face milling, while CNC turning includes machining operations such as grooving, boring, drilling, straight and taper turning, threading, and knurling.

CNC turning is best suited for producing components with axially symmetrical shapes. They include cylinders, disks, cones, and polygons. Meanwhile, CNC milling can produce components with both symmetrical and non-symmetrical shapes.

CNC turning is highly adaptable to many materials, including metals, plastics, and wood. On the contrary, CNC milling has more selective compatibility Cemented Carbide Inserts with raw materials. Therefore, experts usually use CNC milling for materials such as aluminum, stainless, carbon steel, titanium, and nylon.

Even though CNC machines offer numerous advantages, manufacturers must examine the design requirements before settling on the CNC machining operation best fitted for each manufacturing project. If you are ever in doubt, an expert machinist can guide you in choosing the proper CNC machining process for your manufacturing project. Here are some useful tips to guide you in selecting the right machining process:

CNC milling uses rotating cutting tools to subtract materials across a stationary workpiece. So, experts often choose CNC milling for manufacturing projects that do not require cylindrical components. That being said, you can apply CNC milling in machining flat or irregular surfaces. Additionally, you can best choose CNC milling for secondary finishing processes as it provides well-defined design features.

CNC turning involves rotating the workpiece while the cutting tool makes contact to remove excess materials. For this reason, expert machinists select CNC turning for manufacturing projects that require cylindrical or round profiles. Moreover, the high-speed rotation and wide-ranging compatibility of CNC turning operations with different materials make it best suited for large production of tubular parts.

CNC mills and lathes apply in many machining operations across several industries today. They include electrical, woodworking and metalworking, automotive, medical, aerospace, motorcycle industries, etc. Check the application of CNC mills and CNC lathes in custom part fabrication below:

Engine partsGearsFittingsMedical instrumentsBracketsEnclosuresWater pumps, etc.Round ShaftsNozzlesFirearmBall JointsRollersTurbinesFlanges for beams and pipes, etc.

CNC turning is typically used for parts with round features, while CNC milling is more suitable for other shapes. If you’re not sure which process to use, Estoolcarbide’s machining experts can help you choose the right CNC machining service for your project.

In addition, in some cases, CNC milling and CNC turning can be combined to get the best results. So, whether your project requires turning or milling, with our extensive machining experience, your needs can be met to a high standard. Get a quote today and discuss the details with our engineers.

CNC machines have become a staple in many manufacturing companies. These computerized machines incorporate pre-programmed software to automate machining operations, thus making most manufacturing processes more efficient, faster, and precise.

CNC milling and turning remain the most popular CNC manufacturing operations. Even though both processes have certain CNC similarities, there’s much more to their machining methods than meets the eye. Thus, this article examines the differences between CNC turning and milling and their application in fabricating custom components.

Which is better? A lathe or mill?

This mainly depends on your manufacturing project. A CNC lathe is most suitable for the continuous fabrication of cylindrical components due to its higher production efficiency and performance. Conversely, a CNC mill will outperform a lathe when applying finishing features to a custom-designed component.

Is turning cheaper than milling?

To a large extent, manufacturers tend to fabricate turned products at a much lower cost compared to milled components. This is because CNC turning procedures allow the efficient production of various parts within a short period, thus minimizing additional costs sustained due to manufacturing errors.

What are the similarities between milling and turning?

-CNC milling and turning to use computer technology to automate and control machine tools. Therefore, they both minimize human errors to deliver the low volume of quality products within a short period.

-Both processes use subtractive manufacturing techniques.

-Both machining operations generate heat and often require fluids to reduce the heat.

-Milling and turning operations are compatible with workpieces like aluminum, titanium, steel, copper, and an array of thermoplastics.

The Tungsten Carbide Blog: https://stuartwarn.exblog.jp/

How to Use Advanced CNC services Machining Hole Techniques

Posted on August. 12th, 2019, | By Estoolcarbide Project Manager

Hole manufacturing is largely underestimated because the majority of holes we make have trivial precision, small depth, and are only supposed to keep Carbide Drilling Inserts bolts. However, modern high-tech industries ( aerospace and automotive especially) come to the CNC services market with demands for manufacturing parts with extremely precise or deep holes, or for the holes to have a very precise position. Besides advanced CNC machining services, such demands require specific techniques and careful planning.

The hole manufacturing process is actually quite trying from the manufacturing point of view. The tool and the blank can be easily overheated because it’s hard to apply coolants into the hole, the process is not visible to the machinist so he can only rely on the machine tool information and must cut blindly, conducting measurements is hard especially in holes with small diameters. And those are only a few problems with hole manufacturing. So, in order to make precise holes, CNC services always develop and improve machining strategies, they invent new tools and tools to meet the requirements of the client.

Get instant Quote?

Well, drilling itself is a common process and there is nothing interesting bout drilling short holes ut the deeper the hole the harder it is to keep its axis straight while drilling. That is due to the fact that a longer drill is less rigid while it has two cutting edges that cannot be made of identical length. So, the cutting force of the drill sides is different and the drill usually deviates from the straight axis and makes the hole lopsided. This is not acceptable for high precision CNC parts.

That’s why gun drilling has been invented. as the name suggests, it was first used to manufacture long stock guns, where a long but precise hole is the main requirement. Nonetheless, with the development of manufacturing technologies, other industries have adopted gun drilling for their own purposes. The main difference with this strategy is the tool. A gun drill has a single cutting edge so it does not deviate from its course the way a simple drill does. It has a larger chip removal groove that serves as a cooling channel as well. The coolant is pumped through the groove at high pressure and it removes the chip and cools down the drill much better. The downside of this method is that this drill cannot be mounted on a usual CNC milling center, it requires additional tooling.

CNC machine shops use gun drills in the most extreme cases but mostly they try to stick to the universal tools and that’s why there are certain strategies that allow drilling deep holes with simple drills. Firstly, the length of the hole is divided into segments with depths around 3-4 hole diameters. Every time, the drill reaches the end of a segment, it is ejected to let the blank and the tool to cool down and to get all the chips out of the hole.

In order to make a precise hole, CNC drilling is usually carried out with multiple instruments, the first one being considerably smaller than the hole diameter and increasing with the next tool. That is done to decrease cutting force and thus axis deviation due to the reason mentioned above. In addition, consecutive methods are often different from simple drilling:

Core drilling is carried out right after drilling. A core drill has three cutting edges instead of one so it is more stable. Core drills usually process a cut the depth of which is mere 0.5 mm but their absolute advantages are the ability to correct the axis.

Reaming. If your client demands a hole with a tolerance up to IT6 and a very smooth surface finish, you take a reamer and make your machining feed extremely low. A reamer is a tool with a lot of long cutting edges situated along the sides of the tool. It has?front cutting blades but they are extremely small so the cutting depth while reaming is around 0.1-0.05 mm. Due to that and the ultimate precision of the cutting edges, reaming will yield great holes. For smaller holes, reaming is done manually.

Honing is an abrasive process but it can be carried out on a CNC machine tool, however, special honing machines are definitely better. A hone is basically a reamer with abrasive planks instead of cutting blades. Another difference is that the planks can be adjusted for the right diameter. The hone is inserted into the hole and it revolves around its axis while the planks grind the material. Once the hone is ejected, the revolution direction is reversed. As a result, the surface of the hole has crisscrossed microscopic grooves, which make lubrication much more efficient.

A lot of holes require threads, which are comprised of complex thin surfaces and are actually pretty hard to machine. There is a number of strategies for threading but before that,? it is absolutely necessary to carry out countersinking or counterboring. Those two processes create a conical or cylindrical groove at the entrance of the hole. It allows the threading tool to enter correctly and further on helps with assembling the actual parts. So, here are some strategies to threading.

Tap drilling uses a single tool that reminds a bolt but has chip removal grooves and a long conical area at the front to gradually increase cut depth. The machining feed during threading with a taper ( and with any thread for that matter) is the same as the screw pitch. The tap drill is slowly inserted into the hole where each of its spiraling cutting edges gradually cuts off a piece of material to form the thread. Small holes are machined manually, in which case the hole process reminds screwing in a vary tight bolt. The tap drill must be ejected with great care the same way it was inserted. If you forget that and try to eject the tap drill without unscrewing, you can break it and will have to get it out with Electrical Discharge Machining.

Thread milling yields better results because the temperature of the process is lower and it is much easier to apply coolants. A special mill that is 30-40% smaller than the diameter of the hole moves in a spiral along the trajectory of the drill groves and revolves around its axis for efficient cutting. The minimum diameter Tungsten Steel Inserts of the hole depends on the minimum diameter of the mill.

Another strategy is called thread boring. It is actually the same as turning in regards to part setup and the main movements but the tool is manufactured to copy the form of the thread groove. So, it is fed with the screw pitch into the hole of the part and cuts the spiraling surfaces of the thread. It is important to note that boring is great for large holes but can not process holes smaller than 20 mm.

Contact Us-Estoolcarbide?to discover how?precision CNC machining?to design part holes for your project.

The Tungsten Carbide Blog: https://richierory.exblog.jp/